Valves are common components of almost any piping system. Although they can be constructed in many different configurations and sizes, a typical valve will include a few basic elements. These include: a valve body that houses internal components within an internal cavity; inlet and outlet pipes leading to and from the valve body; and a valve member that is positioned within the cavity of the valve body. These components are attached such that fluid entering the valve through the inlet pipe is either allowed to flow through to the outlet pipe by the valve member or prevented from such flow based on the orientation of the valve member within to the valve body.
One type of valve commonly used in some piping systems is the quick closing disk check valve, which is typically employed in systems in which reverse flow through the valve is undesirable. A quick closing disk check valve is typically constructed with a generally circular disk that pivots on hinge pins mounted within the body of the valve. A portion of one surface of the disk rests against a seating surface located in the body of the valve when the valve is in the closed position. The disk pivots about the hinge pins away from the seating surface in response to the flow of fluid through the inlet and outlet ports of the valve. Pivoting of the disk about the hinge pins away from the closed position is resisted by helical springs that surround the hinge pins or other rotation-resisting devices, such as a counterbalancing weight attached to the disk.
One specific problem that can occur with a quick closing disk check valve is misalignment of the disk relative to the seating surface. Because the disk and seating surface form a seal, it is important that the contact between these components be as complete as possible. This can be accomplished by locating the disk properly relative to the seating surface. If, on the other hand, the disk is mounted in a misaligned condition, the seal may be inadequate for the system in which it is installed. Because the tolerances for the seat are quite narrow, proper mounting can be quite difficult to achieve.
One solution offered to address the problem of misalignment is the use of adjustable hinge pins. In this configuration, the hinge pins include both a hollow outer hollow hinge pin and an inner hinge pin core that fits within a bore in the hinge pin and is rotatably adjustable relative to the outer hinge pin within that bore. The hinge pin core is rotatably attached to bearings mounted in the valve disk, and the hinge pin is mounted to the valve body. The centerline of the bore extending through the hinge pin is offset slightly (about 0.105") from the centerline of the hinge pin itself. Also, the hinge pin core is eccentrically mounted onto the disk with a similar 0.105" offset. As a result, rotation of either (a) the hinge pin core within the outer hinge pin or (b) the outer hinge pin relative to the valve body within which it is mounted moves the bearing end of the hinge pin core (and, in turn, the disk) relative to the housing. Thus, the position of the disk relative to the valve seat can be adjusted within a circle of having a diameter of approximately 0.4".
One difficulty with the adjustable hinge pin design (and other quick closing disk check valves) is determining the angle or position to which the disk pivots during fluid flow. Being able to monitor this parameter can be important in determining and regulating volumetric flow. It is important that any sort of device that performs this function operate reliably and without interfering with the operation of the valve itself. Also, such a device should be easily read.